1. Field of the Invention
The present disclosure relates generally to tomographic imaging and, more particularly to nuclear camera housings for use in nuclear medical imaging and methods of construction thereof.
2. Description of the Background Art
In tomographic imaging, a gamma camera or Anger camera system is employed for imaging of the radiation emitted by a radioactive tracer source injected into a patient. After the tracer has been absorbed into the body of the patient the gamma camera can take a picture of the tissue in question, from outside the body, as an aid to diagnosis.
Such known gamma camera consists of detection elements (e.g., a detector head or imaging plane, imaging electronics and the like), which contains a sodium iodide crystal that absorbs the gamma rays and emits the energy as a flash of light. Coupled to the crystal is an array of photomultiplier tubes that converts the light flashes to electronic pulses. Gamma rays emitted from the imaged organ travel radially outward in all directions. A collimator consisting a multiplicity of parallel holes shields the entire crystal permits the passage of only those rays that are traveling in a direction parallel to the collimator through the crystal. The gamma camera further includes a shielding box surrounding the detection elements. The shielding box is typically made of a radiation blocking material (e.g., lead) configured and dimensioned to block unwanted stray radiation from reaching the detection elements. An issue arises as to the degree of shielding necessary to protect the detection elements from unwanted radiation. In order to sufficiently protect the detection elements from the unwanted radiation, the shielding box surrounding the detection elements needs to be massive. As the level of radiation becomes higher for certain procedures, the degree of shielding provided by the shielding box must be increased which in turn increases the size and/or weight of the shielding box.
In the past, a casting process was typically used to fabricate the shielding box, resulting in a single unitary structure having monolithically formed walls and the like. This casting process consists of casting, pre-machining; pour lead, finish machining and painting. The deficiencies for the manufacturing of the shielding box in these manners are extensive tooling, complex machining, high scrap risk and high storage cost. Firstly, the shielding boxes are integrally cast from lead using combinations of permanent tooling and mechanical housings. The tooling can be complex and costly. Secondly, the casting part can also be costly due to the machining required both before and after casting. The casting for the shielding box can be very massive and difficult to maneuver. Thirdly, the entire shielding box has to be scraped if there is anything wrong with the part. Furthermore, the costs associated with storage and/or transporting of the shielding box can also be high. The higher cost associated with storage of the shielding box stemmed from the relatively larger volume and/or increased space required to store the shielding box, while the higher cost associated with transportation of the shielding box stemmed from the relatively larger volume and relatively increased weight of the shielding box.
Moreover, the ability to reconfigure and/or redesign the monolithically formed shielding box is limited and/or undesirable, in that the entire shielding box would typically need to be removed from the site in order to be worked on. In addition, if a redesign of the shielding box and/or gamma camera was contemplated, it was often the case that the entire shielding box needed to be disposed of and replaced with a new, reconfigured shielding box. Accordingly, an increased amount of scrap resulted from having to dispose of the original shielding box.
Accordingly, in view of the above, the need exists for a shielding box and/or a detector housing that is less expensive to manufacture, is less expensive to store and transport, is simpler to recycle and is more adaptable to re-design as compared to monolithicaally formed shielding boxes.